Pentamethylene diisocyanate (PDI), and a modified substance (e.g., a polyisocyanate composition such as isocyanurate) obtained by modifying pentamethylene diisocyanate are used as a material of, for example, polyurethane resins.
Pentamethylene diisocyanate is produced, industrially, for example, by phosgenation of pentamethylenediamine (PDA). Pentamethylenediamine, i.e., a material of pentamethylene diisocyanate, is produced, for example, by biochemical methods such as fermentation and enzymatic methods.
As such a method for producing pentamethylenediamine and pentamethylene diisocyanate, to be specific, Patent Document 1 below has proposed, for example, a production of pentamethylene diisocyanate by decarboxylation of lysine with enzyme to prepare an aqueous hydrochloride solution of diaminopentane, and then precipitation in an organic solvent, removal and purification, and thereafter, phosgenation in a liquid phase or a gas phase.
Patent Document 1 below also describes that pentamethylene diisocyanate is produced such that the hydrolyzable chlorine content is below 10 ppm.
Furthermore, Patent Document 2 below has proposed, for example, that use of pentamethylene diisocyanate having a hydrolyzable chlorine concentration of 100 ppm or less allows production of a modified substance (polyisocyanurate composition) having excellent storage stability at low costs.